Bag-Valve-Mask

Components

Essential components:

Self-inflating bag
In various sizes:
- Infant: 240mL
- Child: 500mL
- Adult: 1600mL
Oxygen source
Air inlet valve
Draws room air into the bag if the oxygen reservoir is empty and the bag is still inflating.
One-way valves
Sit between the self-inflating bag and the:
- Gas source
  Refill valve prevents reflux of gas into the reservoir instead of into the patient.
- Exhalation port Non-rebreathing valve prevents expiration into the self-inflating bag, and forces expiration through the exhalation port (or PEEP valve, if present).
15mm adaptor
For mask or airway device.
High pressure relief valve
Pop-off valve prevents Pip rising excessively (usually at ~40-65cmH₂O, depending on model).

Optional components:

PEEP valve
Partially occludes exhalation port to provide PEEP. May be built-in or sold separately.
Oxygen reservoir
Must be at least as large as the bag. Allows buffering of gas flow into the self-inflating bag (as peak flow will be less than that supplied from the oxygen source), and allows 100% O₂ to be delivered provided the minute ventilation is less the O₂ flow rate.

Steps:

Logistics:

Function:

Can deliver close to 100% oxygen
Minimal dead space
Pop-off valve reduces risk of barotrauma
Highly compatible
15mm adaptor compatible with masks, LMA, ETT, and other in-line airway add-ons (ETCO₂, bronchoscopic Y-piece, etc.).

Logistics:

Misassembly Reusable BVM systems can occasionally have their valves inserted backwards, giving risk of barotrauma and failure of oxygen delivery.

Function:

Less effective for spontaneous ventilation
- Delivered FiO₂ may vary substantially between devices
- Requires sufficient ventilatory effort to open one-way valves
  Failure will result in air entrainment rather than oxygen.
Lower FiO₂ delivered at high MV
Bulky
Easy to hyperventilate
Unable to gauge lung compliance
Risk of barotrauma.
Difficulty assessing delivered tidal volumes

Last updated 2021-08-23